4. Patient has MDD according to the DSM IV-R criteria with an existence of depressed mood (DSM-IV-R Crit. A1) and loss of interest/anhedonia (DSM-IV-R Crit. A2) as confirmed by the MINI, lasting for at least 4 weeks and no longer than 18 months (78 weeks) for the current episode, and causing significant functional impairment (DSM-IV-R MDD C- criterion).